Bump version to 7.8.1

Author: dweiss

README.md

@@ -16,7 +16,7 @@ In order to install a stable version of the plugin,
 run ElasticSearch's `plugin` utility (remember to pick the
 ES-compatible version of the plugin from the table below!).
 
-    bin/elasticsearch-plugin install org.carrot2:elasticsearch-carrot2:7.7.1
+    bin/elasticsearch-plugin install org.carrot2:elasticsearch-carrot2:7.8.1
 
 To install from sources (master branch), run:
 
@@ -91,8 +91,9 @@ Lingo3G 2.x will be supported via a separate
 
 | Clustering Plugin | Elasticsearch          | Carrot2     |     Lingo3G   |
 | ---               |                    --- | ---         |     ---       |
-| (master, unreleased) |                     | 4.0.3       | ext-plugin    |
-| 7.7.1             |                        | 4.0.3       | ext-plugin    |
+| (master, unreleased) |                     | 4.0.4       | ext-plugin    |
+| 7.8.1             |                        | 4.0.4       | ext-plugin    |
+| 7.7.1             |                        | 4.0.4       | ext-plugin    |
 | 7.6.0.1           | 7.6.0                  | 4.0.0-beta3 | not supported |
 | 7.6.0             |                        | 4.0.0-beta3 | not supported |
 | 7.0.0 -> 7.5.0    |                        | 3.16.1      | 1.16.1        |